In recent years laser printers, facsimile machines, image duplicating machines, thermal imaging devices and other printing devices have come to enjoy widespread use in both offices and homes throughout the modern world. At the present time, most of these printing devices employ individual sheets of paper ("cut-sheets") of various sizes. The most common of these sizes are 8.5 inches by 11 inches (standard size) and 8.5 inches by 14 inches (legal size). Many of these devices allow for discharging of the printed sheets of paper from an output source on the front, back, or sides of the device into a low capacity paper tray, with the printed side of the sheet facing upwards. As such the printed papers are successively discharged from the printing device with the printed side of the paper facing upwards. The stack resultant is not properly collated. The first sheet printed is at the bottom of the stack and the last sheet printed is at the top and the printed sides of each sheet are facing up. This resulting stack contains the last page printed on top and the first page printed on the bottom. For proper collation to occur, the sheets of paper must be individually restacked by the user into the proper collated order.
Due to the difficulties encountered with the low paper capacity of the paper tray attached to the printer and the inconvenience of having to individually restack the printed sheets into their proper order, printing devices many times are equipped with electrically powered mechanically driven output stackers. The job of these stackers is to stack large amounts of printed paper in a properly collated order. Current powered stackers are expensive, require frequent maintenance and are in many cases unreliable and prone to malfunction and jamming. Thus a need exists for a low-cost, reliable, high capacity, output paper stacker that is capable of collating the individual sheets paper in their proper order.
Accordingly, the principle object of the present invention is to provide a low-cost, reliable, non-motorized or "passive" paper stacker.
A further objective is to provide a passive paper stacker that will stack the printed paper in a stable and collated stack.
A further objective is to provide a passive paper stacker that has the capability for effectively stacking up to 3000 sheets of cut-sheet paper.
A further objective is to provide a passive paper stacker that can handle both standard and legal sized paper of varying weights, while remaining resistant to paper jams and operating without human supervision.
Additional objectives, advantages and novel features of the invention will be set forth in part in the description that follows, and in part will become apparent to those skilled in the art upon examination of the following or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations pointed out in the claims.